For filling containers, it is known to use either inline or rotary equipment, which are provided with a plurality of suitable tap or filling valves equipped with nozzles closed by a plug. The plug consists of a stem movable along the axis thereof, in order to allow opening and closing the valve in a controlled manner. During the filling operation, the container mouth is sealingly abutted on the valve gasket, thereby creating a closed environment therewith.
When filling glass bottles, the filling valves can provide the possibility of releasing the air contained within the bottle and replace it with sterile air. With carbonated beverages, particularly, the process requires to be carried out with air or other inert gas under pressure, in order to avoid excessive foaming. A release duct is further essential to be provided for the gas which has to leave the bottle, such as to facilitate the completion of the filling operation.
In order to achieve this, the plug is hollow and comprises service co-axial ducts, in order to create a vacuum inside the bottle and subsequently introduce inert gas during the filling operation, as well as to create a vent for the gas.
Furthermore, in a central position relative to the innermost duct, there is normally positioned a suitable probe that extends within the container, reads the filling level, and stops the delivery of the beverage when the preset level has been reached. The probe is coated with isolating material, such as plastic or ceramic material, to avoid that contacts may be created with the metal wall of the surrounding duct, which would result in a short-circuit that would invalidate the probe reading.
A first problem encountered with this type of valves is that the probe coating can be damaged due to wear, thus exposing probe parts that may come in contact with the metal duct, with the above-mentioned consequences.
Furthermore, the probe, which consists of a long and thin stem, requires a centering device. This centering device, which is provided by means of a ring made of isolating material, is necessarily positioned at the mouth of the inner duct and may be thus subjected to bottle burst or excessive foaming. For this reason, the centering device is often damaged. Furthermore, if the latter is placed in the end position, it results to be inserted within the bottle neck, and consequently restrains the gas outflow.